Generally, an exposure unit of an apparatus for manufacturing a liquid crystal display device is provided to perform an exposure process by applying ultraviolet radiation to a glass substrate coated with ph otoresist after providing a photo-mask having a predetermined pattern. Before performing the exposure process, the glass substrate is unloaded from a coating unit for coating the photoresist. At this time, there are a plurality of robot arms and conveyors between the coating unit and the exposure unit for conveying the substrate.
FIG. 1 is a block diagram of an exposure layout according to the related art. The exposure layout explains a sequential process for conveying the glass substrate to the exposure unit.
As shown in FIG. 1, a related art exposure layout is provided with thru-conveyors 11 and 12, a solvent removing unit 20, a temperature reduction unit 30, an in-out turn unit 40, a titler 50, a buffer 60 and a plurality of robot arms 71, 72 and 73.
The thru-conveyor 11 is provided to load a substrate, and the thru-conveyor 12 is provided to unload the substrate.
Then, the substrate coated with photoresist by a coater 2 is conveyed to the solvent removing unit 20 from the thru-conveyor 11. The solvent removing unit 20 removes solvent from the substrate coated with photoresist. The solvent removing unit 20 is formed of an oven having a softbake hot plate SHP. The temperature reduction unit 30 is formed of a cool plate CP for reducing a temperature of the substrate unloaded from the SHP 20. The in-out turn unit 40 changes the progressing direction of the substrate so as to provide the substrate to the next process.
The robot arms 71, 72 and 73 are positioned between each of the components for loading and unloading the substrate. The robot arms include the first robot arm 71, the second robot arm 72 and the third robot arm 73.
The first robot arm 71 receives the substrate coated with photoresist from the coater 2, and then conveys the substrate to the thru-conveyor 11. The first robot arm 71 is provided between the coater 2 and the substrate loading side of the thru-conveyor 11.
The second robot arm 72 receives the substrate unloaded from the thru-conveyor 11, and then conveys the substrate to the SHP 20. Also, the second robot arm 72 receives the substrate from the SHP 20, and then conveys the substrate to the temperature reduction unit 30. Further, the second robot arm 72 receives the substrate from the temperature reduction unit 30, and then conveys the substrate to the in-out turn unit 40.
The SHP 20 is positioned at the substrate unloading side of the thru-conveyor 11. The second robot arm 72 is positioned among the SHP 20, the temperature reduction unit 30 and the in-out turn unit 40, for conveying the substrate to the respective components 20; 30 and 40.
The third robot arm 73 receives the substrate from the in-out turn unit 40, and then conveys the substrate to the exposure unit 3. After completing the exposure process, the substrate is conveyed to the in-out turn unit 40 by the third robot arm 73.
The third robot arm 73 is positioned among the titler 50, the buffer 60, the exposure unit 3 and the in-out turn unit 40, for selectively conveying the substrate to the respective components 50, 60, 3 and 40.
Before performing the exposure process, the substrate is conveyed to the titler 50 by the third robot arm 73 for forming an identification code ID for each substrate.
The buffer 60 includes a cassette for temporarily storing the substrate before being conveyed to the next process. That is, the substrate having the identification code ID is conveyed to the buffer 60 by the third robot arm 73 to be stored temporarily before the exposure unit 3.
Reference number 4 is a vacuum dry unit VCD for drying a coating layer of the substrate unloaded from the coater 2 under low vacuum conditions. The VCD 4 and the SHP 20 are positioned parallel to the thru-conveyor 11.
A method for performing the exposure process on the substrate according to the related art exposure layout may be explained as follows.
First, after coating the substrate with photoresist by the coater 2, the substrate is conveyed to the VCD 4 by the first robot arm 71. After completing the curing process of the substrate in the VCD 4, the substrate is conveyed to the thru-conveyor 11 by the first robot arm 71 (S1).
The second robot arm 72 receives the substrate from the thru-conveyer 11, and then conveys the substrate to the SHP 20 (S2). The SHP 20 removes the solvent from the substrate.
After removing the solvent from the substrate, the substrate is unloaded from the SHP 20 (S3), and then the substrate is conveyed to the temperature reduction unit 30 by the second robot arm 72. After reducing the temperature of the substrate by the temperature reduction unit 30, the substrate is unloaded from the temperature reduction unit 30 (S4), and then is conveyed to the in-out turn unit 40 by the second robot arm 72 (S5).
At this point, the in-out turn unit 40 changes the direction of the substrate conveyed by the second robot arm 72. Then, the third robot arm 73 receives the substrate, which has had its direction changed by the in-out turn unit 40 (S6), and conveys the substrate to the titler 50.
The titler 50 forms the ID for each substrate. Then, the substrate having the ID is unloaded from the titler 50 (S7) and is conveyed to the exposure unit 3 (S9) by the third robot arm 73.
If the exposure unit 3 is in an operation mode, the third robot arm 73 conveys the substrate to the buffer 60 so that the substrate may be temporarily stored in the buffer 60.
After completing the exposure process of the substrate, the substrate unloaded from the exposure unit is conveyed to the in-out turn unit 40 by the third robot arm 73 (S10), and also is conveyed to the thru-conveyor 12 (S11).
In the exposure layout according to the related art, even though the temperature reduction unit is provided so as to adjust the temperature of the substrate before loading the substrate to the exposure unit 3, it is difficult to maintain the most appropriate temperature for each substrate.
The adjustment of the temperature of the substrate by an additional chamber 5 affects the entire exposure layout, or a portion of the layout, including the in-out turn unit 40, the third robot arm 73 and the buffer 60. As a result, it is difficult to adjust precisely the temperature of each substrate.
If the substrate does not have the precise temperature before the exposure process, the dimensions of the substrate may be changed due to the temperature difference. As a result, the position for exposure may be incorrect, and consequently the product may be defective.
Also, the third robot arm 73 performs eight conveyances for the substrate each cycle. Accordingly, a tact time for each cycle is high.
To decrease the tact time for each cycle, another layout for providing an additional robot arm has been proposed. In this case, it is necessary to provide a space for the additional robot arm, and thus the problem of an increased footprint (length of the entire layout) arises. Further, it requires an increase in plant size for the exposure layout.